The present invention relates to a device for determining a length of a middle ear prosthesis.
In order to transmit the sound from an eardrum to a rising bracket or to a rising bracket foot plate in the case of completely or partially defective auditory ossicles, ossicles prostheses are utilized. Since the anatomic properties of ear of different human beings are different to a certain degree, it is necessary to use auditory ossicles prosthesis whose dimensions are adjusted to specific properties of the ear in which it must be utilized. In particular, the distance between the eardrum and the rising bracket footplate in the case of a total reconstruction or the distance between the eardrum and the rising bracket body in the case of a partial reconstruction must be determined.
Conventionally, for this purposes prosthesis mounts with different sizes, in particular with different lengths composed of high grade steel are utilized. The prosthesis mounts are introduced during the operation in the middle ear, until the prosthesis models determining the sizes are found. After the determination of the sizes, the prosthesis models as a rule are again sterilized by steam sterilization in the clinic and are again available for a new size determination.
The prosthesis models are naturally small. The sterilization is therefore very difficult to handle. In order to obtain a sufficient sterilization, preliminarily an exactly defined cleaning process must be carried out. Since the prosthesis mounts are so small, there is a risk that they can be lost during the sterilization or in the course of cleaning. Since the prosthesis mounts are produced of metal, in particular high grade metal, so that they are capable of being sterilized and have a sufficient strength, they are very heavy. This means that they can be tilted during their investigated placement in the middle ear, so that a correct determination of the size of the adjusted prosthesis requires significant skills.